Electronic devices

Abstract

This electronic device comprises: a resin case body having a rectangular opening into which a circuit board is inserted; and a cover to close the opening in the case body. The case body includes a perimeter wall part having a rectangular cross section and forming the opening by means of a pair of first side wall parts facing both surfaces of the circuit board and a pair of second side wall parts connected to the pair of first side wall parts. The perimeter wall part has a pair of first fitting parts provided in a first-side-wall-part area of the annular end face on the opening side, and the cover has a pair of second fitting parts that are press-fitted into the pair of first fitting parts of the case body. Connecting portions between the first side wall parts and the second side wall parts in the perimeter wall part have a recessed part on the inner wall surface side, so as to be thinner than the first side wall parts and the second side wall parts.

Description

[Technical Field]

[0001] The present invention relates to an electronic device, and more particularly to an electronic device in which a circuit board is housed within a housing. [Background Art]

[0002] Vehicles such as automobiles are equipped with an electronic device in which a circuit board is housed within a housing. As a housing for an electronic device, for example, there is one configured by a resin case main body that houses a circuit board, and a cover that covers an opening of the case main body. The resin case main body is manufactured by resin molding using a mold. At this time, due to factors such as residual stress, warpage may occur in the opening of the case main body, resulting in non-uniform height and width of the opening.

[0003] As a countermeasure against such a problem, for example, the technology described in Patent Document 1 has been proposed. In the electronic device described in Patent Document 1, the cover is held in a state fixed to the case by engaging a case-side lock portion provided on the case with a cover-side lock portion provided on the cover side. That is, a snap-fit structure is employed as a method for fixing the cover to the resin case. Furthermore, when engaging the cover-side lock portion with the case-side lock portion, the outer claw portion of the cover, which is closely opposed to the outer surface of the case, presses the case from the outside toward the inside of the case opening, thereby correcting bulging of the case opening (dimensional variation in which the height and width of the opening become non-uniform). [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2021-93446 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, even if the cover-side locking mechanism can be engaged with the case-side locking mechanism by pressing the case with the outer claw portion of the cover to correct the warping of the case opening, as described in Patent Document 1, there is a concern that a gap will remain between the case and the cover due to the warping of the case opening. In automotive electronic devices, this gap can become a pathway for water to enter the case. Therefore, there is a demand to minimize the warping of the case opening that occurs during resin molding using a mold.

[0006] Furthermore, if a snap-fit ​​structure is adopted as a method for fixing a cover to a resin case, as in the technology described in Patent Document 1, the external dimensions of the housing tend to increase due to the snap-fit ​​structure.

[0007] The present invention was made to solve the above-mentioned problems, and its purpose is to provide an electronic device that can suppress deformation of the case opening that occurs during resin molding using a mold and avoid increasing the size of the housing. [Means for solving the problem]

[0008] The present invention includes multiple means for solving the above problems. An example of an electronic device comprises a circuit board constituting an electronic circuit and a housing that houses the circuit board inside, the housing having a housing space for housing the circuit board so as to cover both sides of the circuit board and a resin case body having a rectangular opening for inserting the circuit board into the housing space, and a cover that closes the opening of the case body, the case body having four walls consisting of a pair of first side walls located opposite to both sides of the circuit board and a pair of second side walls connected to one end and the other end of the pair of first side walls The case body includes a peripheral wall portion with a rectangular cross-section that forms the opening, and the peripheral wall portion of the case body has a pair of first fitting portions that are provided in the region of the pair of first side wall portions on the annular end face on the opening side and extend along the extending direction of the annular end face, and the cover has a pair of second fitting portions that are fitted by press-fitting to the pair of first fitting portions of the case body, and the connection portion between the first side wall portion and the second side wall portion of the peripheral wall portion of the case body has a recessed portion on the inner wall surface side which is thinner than the first side wall portion and the second side wall portion. [Effects of the Invention]

[0009] According to one example of the present invention, by forming a press-fit fitting structure with a pair of first fitting parts provided on the case body and a pair of second fitting parts provided on the cover, the cover can be fixed to the case body without providing a snap-fit ​​structure. This makes it possible to improve rigidity by making the pair of first side walls at the opening of the case body thicker while avoiding an increase in the external dimensions of the housing. Furthermore, the recessed portion at the corner of the peripheral wall of the case body (the connection portion between the first side wall and the second side wall) reduces the difference in contact area between the inner wall surface and the outer wall surface with respect to the molding die at the corner of the peripheral wall. This reduces residual stress generated at the corner and suppresses deformation of the opening of the case body. Therefore, deformation of the opening of the case body that occurs during resin molding using a mold can be suppressed, and an increase in the size of the housing can be avoided. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic perspective view showing the external appearance of an electronic device according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view of the electronic device according to the first embodiment, taken from the direction of arrow II-II in Figure 1. [Figure 3] Figure 1 is a perspective view of the case body of the electronic device according to the first embodiment, seen from the opening side. [Figure 4] Figure 3 is a front view showing the case body of the electronic device according to the first embodiment, viewed from the opening side. [Figure 5] Figure 3 is a plan view of the case body of the electronic device according to the first embodiment. [Figure 6] Figure 1 is a perspective view showing the cover of the electronic device according to the first embodiment. [Figure 7] This is an explanatory diagram showing a method for resin molding of the case body of an electronic device according to the first embodiment. [Figure 8] This is a perspective view of the case body of an electronic device according to a second embodiment of the present invention, as seen from the opening side. [Figure 9] This is a perspective view showing the cover of an electronic device according to the second embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the electronic device of the present invention will be described with reference to the drawings. [First Embodiment] First, the configuration of the electronic device according to the first embodiment will be described using Figures 1 and 2. Figure 1 is a schematic perspective view showing the external appearance of the electronic device according to the first embodiment. Figure 2 is a cross-sectional view of the electronic device according to the first embodiment, taken along the line II-II in Figure 1.

[0012] In FIGS. 1 and 2, the electronic device 1 includes a circuit board 2 (only shown in FIG. 2) that constitutes an electronic circuit, and a housing 3 that accommodates the circuit board 2 therein. The electronic device 1 is, for example, mounted on a vehicle not shown in the drawings.

[0013] The housing 3 is composed of a bottomed cylindrical case body 10 that has an accommodation space 10a for accommodating the circuit board 2 and has a rectangular opening 10b on one side for inserting the circuit board 2 into the accommodation space 10a, and a cover 30 attached to the case body 10 so as to close the opening 10b of the case body 10. The case body 10 and the cover 30 are resin molded products. Details of the structures of the case body 10 and the cover 30 of the housing 3 and the molding method thereof will be described later.

[0014] As shown in FIG. 2, the circuit board 2 includes a wiring substrate 5 on which wiring is formed, an electronic component (not shown) mounted on the wiring substrate 5, and a connector 6 mounted on the wiring substrate 5. The wiring substrate 5 is formed in, for example, a rectangular shape, and has a first surface 5a which is a mounting surface on which the connector 6 is mounted, and a second surface 5b which is a back surface of the first surface 5a. The circuit board 2 may be single-sided mounting in which electronic components are mounted on only one of the first surface 5a and the second surface 5b of the wiring substrate 5, or double-sided mounting in which electronic components are mounted on both the first surface 5a and the second surface 5b of the wiring substrate 5. The connector 6 enables electrical connection with an external electronic device, and is arranged such that a part thereof is exposed to the outside of the housing 3 via a connector opening 31a (described later) of the cover 30 of the housing 3.

[0015] Next, details of the configuration and structure of the housing of the electronic device according to the first embodiment will be described with reference to FIGS. 1 to 6. FIG. 3 is a perspective view of the case body of the electronic device according to the first embodiment shown in FIG. 1 as viewed from the opening side. FIG. 4 is a front view (viewed from the opening side) of the case body of the electronic device according to the first embodiment shown in FIG. 3. FIG. 5 is a plan view of the case body of the electronic device according to the first embodiment shown in FIG. 3. FIG. 6 is a perspective view showing the cover of the electronic device according to the first embodiment shown in FIG. 1.

[0016] As shown in Fig. 2, the case body 10 of the housing 3 covers both the first surface 5a and the second surface 5b of the wiring board 5, and is configured to house the circuit board 2 in the housing space 10a so as to surround the outer peripheral edge of the wiring board 5 except for one side where the connector 6 is disposed. As shown in Figs. 1 to 3, for example, the case body 10 is formed in a flat substantially rectangular parallelepiped shape, and is composed of a rectangular bottom wall 11 located on the opposite side of the opening 10b of the case body 10, and a square cylindrical peripheral wall 12 rising from the outer peripheral edge of the bottom wall 11.

[0017] As shown in Fig. 3, the distal end portion of the peripheral wall 12 opposite to the bottom wall 11 side forms the opening 10b, and has a rectangular annular end surface 12a on the opening 10b side. As shown in Figs. 2 to 4, the peripheral wall 12 is composed of four wall parts: a pair of first side wall parts 14 located at positions facing both the first surface 5a and the second surface 5b of the circuit board 2, and a pair of second side wall parts 15 connected to one side end and the other side end of the pair of first side wall parts 14, and is formed to have a rectangular cross section.

[0018] As shown in Figs. 3 and 4, a pair of guide grooves 18 extending from the annular end surface 12a on the opening 10b side of the case body 10 to the bottom wall 11 are provided on the inner wall surfaces 15a of the pair of second side wall parts 15 of the peripheral wall 12. The pair of guide grooves 18 function as a guide when inserting the circuit board 2 into the housing space 10a of the case body 10, and have a function of holding the side ends of the circuit board 2. In addition, as shown in Fig. 2, a holding groove 19 extending between the pair of second side wall parts 15 is provided on the inner wall surface 11a of the bottom wall 11. The holding groove 19 has a function of holding the other side end (the left end in Fig. 2) of the circuit board 2.

[0019] As shown in Figure 2, the annular end face 12a of the peripheral wall 12 on the opening 10b side is the part where the frame portion 32 of the cover 30, described later, abuts and contacts. The annular end face 12a of the peripheral wall 12 is provided with a fitting structure for fixing the cover 30. Specifically, a pair of first fitting portions 21 are provided in the region of a pair of first side wall portions 14 of the annular end face 12a of the peripheral wall 12. The pair of first fitting portions 21 of the peripheral wall 12 are configured as grooves that extend along the extending direction of the annular end face 12a (left-right direction in Figure 4), as shown in Figure 4, for example. The depth D1 of the grooves as the first fitting portions 21 (see Figure 5) is set so that the cover 30 is securely fixed to the case body 10 when the second fitting portion (protruding portion) 34 of the cover 30, described later, is fitted by press-fitting.

[0020] As shown in Figure 5, for example, the peripheral wall 12 is configured such that the opening-side peripheral wall portion 12b, which is located on the opening 10b side including the annular end face 12a, is thicker than the bottom-side peripheral wall portion 12c, which is located on the bottom wall 11 side, in order to form the groove that serves as the first fitting portion 21. This improves the rigidity of the opening-side peripheral wall portion 12b. The length L2 of the thickened portion 12b of the peripheral wall 12 is set to be greater than the depth D1 of the groove that serves as the first fitting portion 21. The thickened portion 12b of the peripheral wall 12 is formed to bulge outward and become thicker than the bottom-side peripheral wall portion 12c. The bottom-side peripheral wall portion 12c is configured to have a thickness that ensures the rigidity required when a groove is not formed. The peripheral wall 12 has a connecting peripheral wall portion 12d that connects the bottom-side peripheral wall portion 12c, which is thinner than the thickened portion 12b, and the opening-side peripheral wall portion 12b, which is the thickened portion. The connecting peripheral wall portion 12d is formed in a tapered shape, with its outer surface widening as it approaches the opening-side peripheral wall portion 12b, which is a thicker portion. The connecting peripheral wall portion 12d connects the opening-side peripheral wall portion 12b and the bottom-side peripheral wall portion 12c without creating a step. Note that the inner wall surfaces of the peripheral wall 12 (the inner wall surfaces of the opening-side peripheral wall portion 12b, the bottom-side peripheral wall portion 12c, and the connecting peripheral wall portion 12d) are configured to coincide in position with the outer wall surface of the peripheral wall 12.

[0021] As shown in Figures 3 and 4, the portion of the peripheral wall 12 on the opening 10b side, including the annular end face 12a, has recessed portions 22 on the inner wall side such that each corner, which is the connection portion between the first side wall portion 14 and the second side wall portion 15, is thinner than the first side wall portion 14 and the second side wall portion 15. In other words, in the portion of the peripheral wall 12 on the opening 10b side, the inner wall surfaces at each corner, which are the connection points between the first side wall portion 14 and the second side wall portion, are formed as concave wall surfaces that form a recess 22 relative to the inner wall surface 14a of the first side wall portion 14 and the inner wall surface 15a of the second side wall portion 15, so that their thickness is smaller than the thickness t1 of the first side wall portion 14 and the thickness t2 of the second side wall portion 15, and they are closer to the outer wall surface 14b of the first side wall portion 14 and the outer wall surface 15b of the second side wall portion 15 than the inner wall surface 14a of the first side wall portion 14 and the inner wall surface 15a of the second side wall portion 15.

[0022] The recessed portion 22 on the inner wall surface of each corner is formed to include an arc-shaped concave surface. The arc-shaped concave surface can avoid the occurrence of stress concentration. It is also possible to form a concave wall surface using polygonal surfaces for the recessed portion 22. The recessed portion 22 on the inner wall surface of each corner extends from the position of the annular end surface 12a to a position at least half the length L4 of the depth length D3 of the case body 10, from one end (annular end surface 12a) on the opening 10b side to the other end (outer wall surface of the bottom wall 11). As will be described in detail later, a weld region W is formed in the case body 10, which is the part where the leading edges of the flowing resin merge when resin molding is performed using a mold. As shown in Figure 5, there is a concern that the weld region W may be formed from the annular end surface 12a to half the length of the depth length D3 of the case body 10. The weld region W is a part that tends to have reduced strength, and it is necessary to suppress the deformation of the weld region W. Therefore, the recessed portion 22 is configured to extend to the area where the occurrence of the weld zone W is a concern.

[0023] The cover 30 of the housing 3 is composed of a rectangular cover body 31 for closing the opening 10b of the case body 10, and a rectangular frame portion 32 provided on the outer edge of the cover body 31, as shown in Figures 1 and 2, for example. The cover body 31 is provided with a connector opening 31a for exposing a portion of the connector 6 to the outside of the housing 3.

[0024] As shown in Figure 2, the frame portion 32 is the part that fixes the cover 30 to the case body 10, and has a contact surface 32a that abuts against the annular end 12a of the case body 10. Of the contact surface 32a of the frame portion 32, the portion that abuts against the region of the pair of first side wall portions 14 of the annular end surface 12a of the case body 10 is provided with a pair of second fitting portions 34 that are fitted by press-fitting into a pair of first fitting portions 21 of the case body 10. The second fitting portions 34 of the cover 30 are configured as protruding portions that are press-fitted into the grooves 21 of the case body 10, for example, as shown in Figures 2 and 6. The protruding portions as the second fitting portions 34 of the cover 30 extend along the extending direction of the frame portion 32.

[0025] The dimensional relationship between the protruding portion of the cover 30 as the second fitting portion 34 and the groove of the case body 10 as the first fitting portion 21 is set to, for example, a light press-fit range. Specifically, as an example of a light press-fit range, according to JIS B0401-2 (1998), examples include combinations of H6 on the groove 21 side and js5, jk5, m5, n5, n6 on the protruding portion 34 side, or combinations of H7 on the groove 21 side and k6, m6, n6, p6 on the protruding portion 34 side.

[0026] The frame portion 32 is provided with a pair of notches 35 connected to the guide groove 18 of the case body 10 in the portion of the contact surface 32a that contacts the area of ​​the pair of second side wall portions 15 of the annular end face 12a of the case body 10. The pair of notches 35 are configured to hold the corner of one side edge of the circuit board 2 where the connector 6 is located. The circuit board 2 is sandwiched between the retaining groove 19 of the bottom wall 11 of the case body 10 and the pair of notches 35 of the frame portion 32 of the cover 30, thereby positioning and holding the circuit board 2 within the housing space 10a of the case body 10.

[0027] Next, the method for molding the case body of the electronic device according to the first embodiment will be explained with reference to Figure 7. Figure 7 is an explanatory diagram showing the resin molding method for the case body of the electronic device according to the first embodiment.

[0028] The case body 10 of the electronic device 1 shown in Figure 3 is resin-molded using a mold that combines a female mold (cavity) 101 and a male mold (core) (not shown) as shown in Figure 7. The molding system 100 for the case body 10 according to this embodiment shown in Figure 7 is a multi-cavity system having many female molds (cavities) 101 and corresponding male molds (cores). In the molding system 100, a nozzle 102 for injecting molten resin is connected to many female molds (cavities) 101 via a runner 103. The multi-cavity molding system 100 improves yield, enabling low-cost production. The cover 30 can also be resin-molded using a similar molding system.

[0029] The female mold (cavity) 101 is positioned such that the portion corresponding to the bottom wall 11 of the case body 10 faces upwards, and the portion corresponding to the opening 10b of the peripheral wall 12 faces downwards. The female mold (cavity) 101 has a gate 101a formed in the portion corresponding to the bottom wall 11 of the case body 10. Molten resin that flows into the female mold (cavity) 101 through the gate 101a flows from the portion corresponding to the bottom wall 11 of the case body 10 toward the portion corresponding to the annular end face 12a. As a result, as shown in Figure 5, a weld area W is likely to be formed in the center of the opening side of the pair of first side wall portions 14 in the peripheral wall 12 of the case body 10. There is a concern that the weld area W formed in this way will extend from the annular end face 12a to half the length of the depth length D3 of the case body 10.

[0030] Furthermore, in the molding system 100 shown in Figure 7, mold opening is performed by the downward movement of a male mold (core) (not shown). The case body 10 can be released from the male mold (core) by pushing it upward using a cylindrical ejector pin P, for example, as shown in Figure 5. The ejector pin P is positioned, for example, to push out the corner of the annular end face 12a of the peripheral wall 12. Alternatively, instead of a cylindrical ejector pin P, a plate-shaped corner pin P can be used, as shown in Figure 7. In this configuration, the pin is positioned to push out the area of ​​a pair of first side wall portions 14 or second side wall portions 15 on the annular end face 12a of the peripheral wall 12.

[0031] In this embodiment, as shown in Figures 3 and 4, each corner of the peripheral wall 12 of the case body 10 on the opening 10b side has a recessed portion 22 on the inner wall surface side such that it is thinner than the first side wall portion 14 and the second side wall portion 15. As a result, the difference between the contact area of ​​the outer wall surface with the female mold (cavity) 101 and the contact area of ​​the inner wall surface with the male mold (core) at the corner of the portion of the peripheral wall 12 on the opening 10b side is smaller than when the recessed portion 22 is not provided, so that residual stress generated at the corner during resin molding using the mold of the case body 10 is reduced. As a result, warping of the opening of the case body 10 can be suppressed.

[0032] Furthermore, in this embodiment, as shown in Figures 3 and 4, grooves, which are the first fitting portion 21, are provided in the region of a pair of first side wall portions 14 of the annular end face 12a of the case body 10 as a press-fit fitting structure for fixing the cover 30 to the case body 10. Therefore, the cover 30 can be fixed to the case body 10 without providing a snap-fit ​​structure, eliminating the need for a sliding mold required when forming a snap-fit ​​structure, and simplifying the molding system 100 for the case body 10.

[0033] As described above, the electronic device 1 according to the first embodiment comprises a circuit board 2 constituting an electronic circuit and a housing 3 that houses the circuit board 2. The housing 3 comprises a resin case body 10 having a housing space 10a that houses the circuit board 2 so as to cover both sides 5a and 5b of the circuit board 2, and a rectangular opening 10b for inserting the circuit board 2 into the housing space 10a, and a cover 30 that closes the opening 10b of the case body 10. The case body 10 includes a peripheral wall portion with a rectangular cross-section (the portion of the peripheral wall 12 on the opening 10b side) that forms the opening 10b by four wall portions: a pair of first side wall portions 14 located opposite both sides 5a and 5b of the circuit board 2, and a pair of second side wall portions 15 connected to one end and the other end of the pair of first side wall portions 14. The peripheral wall portion of the case body 10 has a pair of first fitting portions 21 that are provided in the region of a pair of first side wall portions 14 of the annular end face 12a on the opening 10b side and extend along the extending direction of the annular end face 12a. The cover 30 has a pair of second fitting portions 34 that are fitted by press-fitting to the pair of first fitting portions 21 of the case body 10. The connection portion between the first side wall portion 14 and the second side wall portion 15 in the peripheral wall portion of the case body 10 has a recessed portion 22 on the inner wall surface side which is thinner than the first side wall portion 14 and the second side wall portion 15.

[0034] With this configuration, a press-fit fitting structure is formed by a pair of first fitting parts 21 provided on the case body 10 and a pair of second fitting parts 34 provided on the cover 30. This allows the cover 30 to be fixed to the case body 10 without the need for a snap-fit ​​structure. As a result, the pair of first side wall parts 14 at the opening of the case body 10 can be made thicker to improve rigidity while avoiding an increase in the external dimensions of the housing 3. Furthermore, the recessed part 22 at the corner of the peripheral wall of the case body 10 (the part of the peripheral wall 12 on the opening 10b side) (the connection part between the first side wall part 14 and the second side wall part 15) reduces the difference in contact area between the inner wall surface and the outer wall surface with respect to the mold at the corner of the peripheral wall. This reduces residual stress at the corner and suppresses deformation of the opening of the case body 10. Therefore, deformation of the opening of the case body 10 that occurs during resin molding using a mold can be suppressed, and an increase in the size of the housing 3 can be avoided.

[0035] Furthermore, by suppressing deformation of the opening in the case body 10, the formation of gaps between the case body 10 and the cover 30, which would serve as pathways for water to enter the case body 10, is suppressed. In addition, by setting the press-fitting structure between the case body 10 and the cover 30 to a tolerance range of light press-fitting, it becomes possible to ensure a sealed structure of the housing 3. As a result, water resistance can be maintained with only the press-fitting structure between the first fitting portion 21 of the case body 10 and the second fitting portion 34 of the cover 30.

[0036] Furthermore, in the case body 10 according to this embodiment, the recessed portion 22 at the connection portion (corner) between the first side wall portion 14 and the second side wall portion 15 of the peripheral wall portion (the portion of the peripheral wall 12 on the opening 10b side) is formed to include an arc-shaped concave curved surface.

[0037] This configuration makes it possible to avoid stress concentration on the inner wall surface side of each corner of the peripheral wall.

[0038] Furthermore, in this embodiment, the recessed portion 22 extends from the position of the annular end face 12a to a position L4 or more, which is half the length of the depth D3, within the depth D3 from one end to the other end of the case body 10 on the opening 10b side.

[0039] With this configuration, even when the mold gate is positioned opposite the opening 10b of the case body 10 in order to shorten the molding time of the case body 10, and a weld zone W is formed in the depth direction from the annular end face 12a side of the case body 10, the recessed portion 22 can be extended to a position corresponding to the length at which the weld zone W, which is prone to stress concentration, is expected to occur, thereby suppressing deformation due to a decrease in the rigidity of the case body 10.

[0040] Furthermore, in this embodiment, the pair of first fitting portions 21 of the case body 10 are grooves that extend along the extending direction of the annular end face 12a, and the pair of second fitting portions 34 of the cover 30 are protruding portions that are press-fitted into the grooves 21 of the case body 10.

[0041] With this configuration, the fitting structure for fixing the case body 10 and the cover 30 becomes a simplified press-fit structure, which simplifies the molds used for resin molding of the case body 10 and the cover 30.

[0042] Furthermore, in the case body 10 according to this embodiment, the peripheral wall portion (the portion of the peripheral wall 12 on the opening 10b side) is formed as a thick-walled portion in which the portion from the annular end face 12a to at least the position of the depth D1 of the groove which is the first fitting portion 21 (opening side peripheral wall portion 12b) bulges outward and becomes thicker than the rest of the case body 10 (bottom side peripheral wall portion 12c).

[0043] With this configuration, the rigidity of the case body 10 is improved by making the portion on the opening 10b side a thickened portion 12b, thereby suppressing deformation caused by the load applied when demolding the case body 10 and when assembling the cover.

[0044] Furthermore, the case body 10 according to this embodiment has a connecting peripheral wall portion 12d that connects a thin-walled portion (bottom peripheral wall portion 12c), which is thinner than the opening-side peripheral wall portion 12b (thick-walled portion), to the opening-side peripheral wall portion 12b (thick-walled portion). The connecting peripheral wall portion 12d (connecting portion) is formed in a tapered shape, with its outer surface widening so that its thickness increases as it approaches the opening-side peripheral wall portion 12b, which is the thick-walled portion.

[0045] With this configuration, by forming the connecting peripheral wall portion 12d in a tapered shape with an expanding outer surface, the opening-side peripheral wall portion 12b, which is a thicker portion, and the bottom-side peripheral wall portion 12c, which is a relatively thinner portion, can be connected without creating a step. Therefore, stress concentration in the connecting peripheral wall portion 12d can be avoided.

[0046] [Second Embodiment] Next, an electronic device according to a second embodiment of the present invention will be described with reference to Figures 8 and 9. Figure 8 is a perspective view of the case body of the electronic device according to the second embodiment of the present invention, viewed from the opening side. Figure 9 is a perspective view showing the cover of the electronic device according to the second embodiment. In Figures 8 and 9, parts with the same reference numerals as those shown in Figures 1 to 7 are similar parts, so a detailed explanation of them will be omitted.

[0047] The difference between the electronic device according to the second embodiment shown in Figures 8 and 9 and the first embodiment is that the press-fitting structure of the housing's case body 10A and cover 30A is reversed. The other configurations and structures of the electronic device according to the second embodiment are the same as those of the electronic device 1 according to the first embodiment, and their description is omitted.

[0048] Specifically, as shown in Figure 8, the annular end face 12a of the peripheral wall 12 of the case body 10A is provided with a pair of protruding portions as first fitting portions 21A in the region of a pair of first side wall portions 14. The protruding portions as first fitting portions 21A project outward from the annular end face 12a toward the cover 30A and extend along the direction of extension of the annular end face 12a (left-right direction in Figure 8).

[0049] In the cover 30A, as shown in Figure 9, a pair of grooves are provided as second fitting portions 34A in the portion of the contact surface 32a of the frame portion 32 that contacts the region of the pair of first side wall portions 14 of the annular end surface 12a of the case body 10, into which the pair of protruding portions that serve as first fitting portions 21 of the case body 10 are press-fitted. The grooves as the second fitting portions 34A of the cover 30 extend along the extending direction of the frame portion 32.

[0050] In this embodiment, the protrusion 21A provided on the annular end face 12a of the case body 10A and the groove 34A provided on the contact surface 32a of the cover 30A constitute a press-fit structure that fixes the cover 30A to the case body 10A. Therefore, the cover 30A can be fixed to the case body 10A without providing a snap-fit ​​structure, eliminating the need for a sliding mold required when forming a snap-fit ​​structure, and simplifying the molding system 100 for the case body 10A.

[0051] According to the electronic device of the second embodiment described above, similar to the first embodiment, a press-fit fitting structure is formed by a pair of first fitting portions 21A provided on the case body 10A and a pair of second fitting portions 34A provided on the cover 30A. This allows the cover 30A to be fixed to the case body 10A without the need for a snap-fit ​​structure. As a result, the rigidity of the pair of first side wall portions 14 at the opening of the case body 10A can be improved by making them thicker, while avoiding an increase in the external dimensions of the housing 3. Furthermore, the recessed portion 22 at the corner of the peripheral wall portion of the case body 10A (the portion of the peripheral wall 12 on the opening 10b side) (the connection portion between the first side wall portion 14 and the second side wall portion 15) reduces the difference in contact area between the inner wall surface and the outer wall surface with respect to the mold at the corner of the peripheral wall portion. This reduces residual stress at the corner and suppresses deformation of the opening of the case body 10A. Therefore, deformation of the opening of the case body 10A that occurs during resin molding using a mold can be suppressed, and an increase in the size of the housing 3 can be avoided.

[0052] Furthermore, by suppressing deformation of the opening in the case body 10A, the formation of a gap between the case body 10A and the cover 30A, which would serve as a water ingress path into the case body 10A, is suppressed. In addition, by setting the press-fitting structure between the case body 10A and the cover 30A to a tolerance range of light press-fitting, it is possible to ensure a sealed structure of the housing 3. As a result, water resistance can be maintained solely by the press-fitting structure between the first fitting portion 21A of the case body 10A and the second fitting portion 34A of the cover 30A.

[0053] Furthermore, in this embodiment, the pair of first fitting portions 21A of the case body 10A protrude from the annular end face 12a toward the cover 30A and are ridges that extend along the extending direction of the annular end face 12a. The pair of second fitting portions 34A of the cover 30A are grooves into which the ridges that make up the pair of first fitting portions 21A of the case body 10A are press-fitted.

[0054] With this configuration, the fitting structure for fixing the case body 10A and the cover 30A becomes a simplified press-fit structure, which simplifies the molds for resin molding of the case body 10A and the cover 30A.

[0055] [Other embodiments] It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. The embodiments described above are explained in detail for the purpose of making the present invention easy to understand, and are not necessarily limited to those having all the configurations described. It is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0056] For example, the embodiment described above shows an example in which the connector 6 is mounted on the circuit board 2. However, electronic devices can also be configured in which the connector is not mounted on the circuit board, for example, when communicating with external electronic devices via communication.

[0057] Furthermore, in the above-described embodiment, an example was shown in which the recessed portion 22 at the corner of the case body 10, 10A (the connection portion between the first side wall portion 14 and the second side wall portion 15) is formed from the annular end face 12a to a position L4 that is more than half the depth length D3 of the case body 10, 10A. However, it is also possible to configure the recessed portion 22 to extend only to the extent of the opening-side peripheral wall portion 12b, which is a thickened portion. However, with this configuration, the effect of suppressing warping (deformation) of the opening of the case body 10, 10A may be reduced compared to the above-described embodiment.

[0058] Furthermore, in the above-described embodiment, an example was shown in which the peripheral wall 12 of the case body 10, 10A has a rectangular cross-section from the annular end face 12a to the bottom wall 11. However, as long as the peripheral wall 12 has a rectangular cross-section up to the position where the recessed portion 22 at the corner extends, it is also possible for the cross-section of the portion thereafter to not be rectangular. [Explanation of Symbols]

[0059] 1…Electronic device, 2…Circuit board, 5a…First surface, 5b…Second surface, 3…Housing, 10, 10A…Case body, 10a…Housing space, 10b…Opening, 12…Peripheral wall, 12a…Annular end face, 12b…Opening side peripheral wall (thick part), 12c…Bottom side peripheral wall (thin part), 12d…Connecting peripheral wall (connecting part), 14…First side wall, 15…Second side wall, 21…First fitting part (groove), 21A…First fitting part (protruding part), 22…Recess, 30, 30A…Cover, 34…Second fitting part (protruding part), 34A…Second fitting part (groove)

Claims

1. A circuit board that constitutes an electronic circuit, The system comprises a housing that houses the aforementioned circuit board inside, The aforementioned enclosure is A resin case body having a housing space for housing the circuit board so as to cover both sides of the circuit board, and having a rectangular opening for inserting the circuit board into the housing space, The case body comprises a cover that closes the opening, The case body includes a rectangular cross-sectional peripheral wall portion that forms the opening, formed by four wall portions: a pair of first side wall portions located opposite both sides of the circuit board, and a pair of second side wall portions connected to one end and the other end of the pair of first side wall portions. The peripheral wall portion of the case body is provided in the region of the pair of first side wall portions of the annular end face on the opening side, and has a pair of first fitting portions that extend along the extending direction of the annular end face. The cover has a pair of second fitting portions that are press-fitted to the pair of first fitting portions of the case body, The connection portion between the first side wall portion and the second side wall portion in the peripheral wall portion of the case body has a recessed portion on the inner wall surface side that is thinner than the first side wall portion and the second side wall portion. An electronic device characterized by the following features.

2. In the electronic device described in claim 1, The recessed portion in the connecting portion of the peripheral wall is formed to include an arc-shaped concave surface. An electronic device characterized by the following features.

3. In the electronic device described in claim 1, The recessed portion in the connecting part of the peripheral wall extends from the position of the annular end face to a position at least half the length of the depth from one end to the other end of the opening side of the case body. An electronic device characterized by the following features.

4. In the electronic device described in claim 1, The pair of first fitting portions of the case body are grooves that extend along the extending direction of the annular end face, The pair of second fitting portions of the cover are protruding portions that are press-fitted into the grooves of the case body. An electronic device characterized by the following features.

5. In the electronic device described in claim 1, The pair of first fitting portions of the case body are projections that protrude from the annular end face toward the cover side and extend along the extending direction of the annular end face. The pair of second fitting portions of the cover are grooves into which the protruding portions of the case body are press-fitted. An electronic device characterized by the following features.

6. In the electronic device according to claim 4, The peripheral wall portion of the case body is formed as a thick-walled portion, where the portion extending from the annular end face to at least the depth of the groove bulges outward and becomes thicker than the rest of the case body. An electronic device characterized by the following features.

7. In the electronic device according to claim 6, The case body has a connecting portion that connects a thin-walled portion, which is thinner than the thick-walled portion, to the thick-walled portion. The connecting portion is formed in a tapered shape, with its outer surface widening as it approaches the thickened portion. An electronic device characterized by the following features.

Images